Fatal error: Uncaught Error: Class "yii\db\Migration" not found in /users/quirl/www/filemanager/spark/protected/humhub/modules/friendship/migrations/m160216_160119_initial.php:6 Stack trace: #0 {main} thrown in /users/quirl/www/filemanager/spark/protected/humhub/modules/friendship/migrations/m160216_160119_initial.php on line 6